Amphipods can be distinguished from copepods as able to seen at a distance. * Amphipods range in size from 5-10mm, where as copepods range from 1-3mm. * This listing is for a variety of both. * Amphipods and copepods make excellent food for picky eaters like seahorses. Mandarin gobies love th * Tanks can be seeded with them by introducing ~500 per 25 gallons or through the use of an upstream f